The government, led by president Dilma Rousseff, says the dam is necessary if Brazilian energy production is to keep pace with its economy. This grew 7.5% in 2010, but
dropped off significantly to 2.7% last year

But indigenous and environmental groups, among others, counter that Belo Monte will displace tens of thousands of river-dwellers and bring violence, social chaos and environmental destruction – including deforestation – to the Amazon state of Pará

James Cameron, the Oscar-winning director, visited the area last year to lend his support to the anti-dam campaign. "If this goes forward then every other hydroelectric project in the Amazon basin gets a blank cheque," Cameron said. "It's now a global issue. The Amazon rainforest is so big and so powerful a piece of the overall climate picture that its destruction will affect everyone"

Supporters say hydropower is Brazil's best clean-energy option, but reservoirs have high emissions of CO2 and methane (with a warming effect 25 times stronger than CO2), because of decaying matter underwater

A further concern is that much of Belo Monte's energy output seems destined to power energy-intensive industries in the region, mostly mining and aluminium, meaning more deforestation and community displacement in the future

River communities are uneasy. "I do not accept the Belo Monte dam," said Mokuka Kayapó, an indigenous leader. "The forest is our butcher. The river, with its fish, is our market. This is how we survive"

The licence obtained by Norte Energia SA, a consortium almost entirely funded by state money, allows 238 hectares of forest to be cut down in order to open roads and basic infrastructure for the workers